Implantable cardiac stimulation devices, such as, for example, automatic implantable cardioverter defibrillators (AICDs) and pacemakers, have been proven reliably effective in treating a variety of arrhythmias, including cardiac arrest. However, at least one environmental circumstance has proven to be problematic for effective delivery of electrotherapy signals to the heart of the patient. More specifically, the amount of energy delivered to the heart of a patient by pacing pulses, such as those used in the treatment of cardiac arrhythmias, may be reduced significantly in the presence of strong radio frequency (RF) signals, such as those produced during an magnetic resonance imaging (MRI) scan of the patient. In at least some instances, the reduction of delivered energy may be traced to an attenuation of the pacing pulses as applied to the heart.
With the above aspects in mind, as well as others not explicitly discussed herein, various embodiments of an implantable cardiac stimulation device and pulse generator used therein, as well as methods of operating such devices, are disclosed herein.